Monitoring of vital signs is an essential element in intensive care units and other hospital departments. Medical sensors-like Pulse Oximeter (SpO2) or Non-Invasive Blood Pressure (NIBP)—are currently wired to bedside monitors, which analyze, interpret and visualize the patient's waveforms, numeric values and alarms. This set-up ties patients to their beds, which is inconvenient for them and complicates work for caregivers. It makes therefore sense to develop wireless monitoring systems. For cost reasons, these new systems will not be built from scratch but rather based on preceding systems by replacing the wired links by wireless links.
In order to turn a wired link (serial line) into a wireless link, the sender (e.g. the medical measurement sensor) and the receiver (e.g. the patient monitor to which the sensor is connected) need to be provided with a radio module each. The wireless link between the radio modules of sender and receiver replaces the original wired connection. Nevertheless the original wire-based protocol may not be suitable for wireless transmission because:                The bandwidth it uses is excessive for the wireless technology used.        The packet size is not feasible (or is not efficient) for the wireless technology used.        The packet frequency is not feasible (or is not efficient) for the wireless technology used.        
Data compression could be used in order to overcome these problems. Yet, if the data to be compressed is real-time data, data compression may not be an option or lead to unsatisfactory results only, because the compression algorithm does not have enough time to gather enough data to perform an efficient compression. Furthermore, data compression being rather CPU-intensive a high energy consumption should be expected. High energy consumption is unwanted in battery-powered devices.
Often the protocol must be modified to be made suitable for the wireless link. This can be done in two ways:                The protocol between sender and receiver is modified. In this way the radio modules of sender and receiver can blindly forward the packets they receive over the serial line.        The protocol between sender and receiver is not modified. However the radio modules of sender and receiver need to implement a modification of the original protocol to talk to each other. Since sender and receiver are unmodified, their respective radio modules still have to support the original protocol on the serial line to communicate with them. The wireless modules have then a translating role.        
The second option is usually preferred due to several reasons:                It does not require changing the software of sender or receiver (which is sometimes inaccessible).        It is usually much easier and cheaper to carry out device-external modifications (modifications of a medical sensor may require dramatic changes in the architecture of the entire patient monitor and all its subcomponents).        It guarantees that the wired link will continue to work as it did before when the wireless link is replaced back with the original wired link.        
Although, in most cases, the option of an unmodified protocol between sender and receiver is the best option, it still has the disadvantage to require the wireless modules to be programmed with the protocols that enable them to talk to each other and to their hosts (the sender or the receiver). This requires access to the software of the wireless modules—which is not always accessible—and has to be done for every new type of device and/or for every new device combination (e.g. for a patient monitor of type A and an SpO2 sensor, for a patient monitor of type B and the same SpO2 sensor, for the patient monitor of type A and an NIBP sensor, etc.). All that caters for high development costs of any wireless system developed on the basis of a wired system.
Note that the roles of sender and receiver may coincide on the same device so that two devices (e.g. sensor and its patient monitor) communicate with each other in a bidirectional fashion. Moreover the communication system may comprise more than two devices (e.g. patient monitor and two different sensors). The problems described above also apply to the latter cases and so does the present invention.